What kind of fan clutch do I have?

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
Is it possible from the pics below to tell what kind of fab clutch I have? The truck is a 97, first used in January of that year. From its condition does it appear salvageable or would it be better to opt for a new one?

If anyone could point me towards a step by step walkthrough of rebuilding/refilling one of these, I’d appreciate it. Also, what weight of fluid would be recommended for an Arkansas summer?

Finally, I’ve been told an impact is all but essential to avoid rounding the heads on the bolts, which I suppose would require having the radiator out to reach in there. Has everyone found this to be the case?
9FCB4820-6E91-4D61-A96B-FD8345262E86.jpeg
 
Joined
Jan 19, 2005
Messages
3,512
Location
South west utah
Finally, I’ve been told an impact is all but essential to avoid rounding the heads on the bolts, which I suppose would require having the radiator out to reach in there. Has everyone found this to be the case?

Not sure on the other questions but you should be able to get nuts off with an extra long box end wrench. Just avoid an open end wrench. If your really worried about it spray them with some penetrating fluid once every day for a few days before you take them out.
 

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
Not sure on the other questions but you should be able to get nuts off with an extra long box end wrench. Just avoid an open end wrench. If your really worried about it spray them with some penetrating fluid once every day for a few days before you take them out.
Thanks, I'm mainly trying to figure out if it's an Eaton or Aisin "black hub" since the rebuild process differs accordingly. I read in another thread the later Aisins have subpar performance.
 

Irish Reiver

SILVER Star
Joined
Oct 24, 2015
Messages
2,124
Location
Orlando, Florida
Pretty sure its not OEM. My black Aisin is unmistakably black.
Why do you think it is not working? They are fairly easy to test.
The nuts are not difficult. As @leonard_nemoy says just make sure you don't use an open end wrench. A good six sided wrench will make short work of them. You may need to use a pry bar on 2 of the studs to stop the hub spinning.
If you do end up getting a new on the blue on off rockauto is very affordable. Test it before you fit it. Good chance you won't need to mess with new fluid.
 

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
Pretty sure its not OEM. My black Aisin is unmistakably black.
Why do you think it is not working? They are fairly easy to test.
The nuts are not difficult. As @leonard_nemoy says just make sure you don't use an open end wrench. A good six sided wrench will make short work of them. You may need to use a pry bar on 2 of the studs to stop the hub spinning.
If you do end up getting a new on the blue on off rockauto is very affordable. Test it before you fit it. Good chance you won't need to mess with new fluid.
Im not sure there’s anything wrong with it, I’m just trying to get my temps down. I saw up to 215f the other day going uphill with 2 canoes on top.
 

clx16

SILVER Star
Joined
Oct 26, 2017
Messages
1,961
Location
Alpharetta GA
Im not sure there’s anything wrong with it, I’m just trying to get my temps down. I saw up to 215f the other day going uphill with 2 canoes on top.
With overdrive on or off?
 

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
With overdrive on or off?
I had OD off, went down to 2nd on steep sections. I smelled a burnt clutch/brake type odor when I stopped, hopefully not the clutches burning up..
 
Joined
Sep 15, 2016
Messages
1,052
Location
Chattanooga, TN
My '97 had an Eaton on it when I bought it and I think many later year 1FZFEs came with Eaton's originally. Once the clutch is out and the plastic fan removed you can easily compare with pics online and figure out what you have, as long as it's one of the common ones (aisin black, aisin blue, eaton). Folks report good results with a rebuilt Eaton but I replaced mine with an Aisin blue.

Good pics of the Eaton here:

They all work the same way, though the internals vary a bit as does oil capacity. Regarding evaluating an old clutch I'd say the main points are below. I'd trash the clutch if isn't a yes on all of these points:
  • Is it one of the known/trusted variants?
  • Does it hold oil without leaking?
  • Is the bearing smooth/quiet?
  • Does the temp spring and plate rotation mechanism work smoothly?
    • Can test this with a heat gun if it's assembled, just watch to see if the input shaft turns, it's easier to see this with it split in half.

I'd guess that 15k or higher CST will work fine for your location. I'm running 15k CST in my Aisin blue hub and have driven around a lot of the country (towing in summer included) with good results. In terms of oil, making sure it has enough oil in it may be more important than, or just as important as, the weight. These days folks are typically running heavier oils than 15k CST as I understand it.

The temp at which the fan starts to open is also very important and seems likely to be off on an older unit given the heat cycles it will have seen.

With a new or old clutch you need to check/set the opening temps in my opinion. To do this, put the front half of the clutch in a double boiler, with a candy thermometer in the water and closely watch to see at what temps the oil ports start to open, are half open and are fully open. Record those temps, adjust as needed and then test/monitor engine temps to verify your adjustment. Correlate your typical operating temps with the noted fan clutch opening temps to help you track adjustments/performance.

You don't want the fan clutch to open too soon. Keep in mind that the coolant thermostat will likely open around 180 degrees (coolant temp) and more air through the rad below that temp is just wasted HP/Fuel. Air passing through the radiator will result in a different temp at the fan clutch so the setup numbers on the clutch won't directly match coolant temps.

My goal was to keep the coolant temps below 210F when pushing hard. When I first purchased my Aisin blue hub I couldn't drive to my house (at the top of a hill) and then idle without the AC shutting off (this happens around 220F). I changed the clutch oil (to 15k cst) and it was better but still didn't pass that test. I set the ports to start opening sooner and that resolved the issue. I ended up setting it so that the small hole is 50% open at 110 degrees. Side note: I had cleaned and sealed the radiator/condensor, etc. before turning to the fan clutch to dial in temps.

This is 1 banana work in my opinion. It's also effective and satisfying. The following should fill in gaps in what I've written above though there are other threads out there aplenty. Keep in mind that there is some variety in opening temps and oil weights used from thread to thread and over time.

 
Last edited:

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
Not a big help but my '97 had an Eaton on it when I bought it and I think many later year 1FZFEs came with Eaton's originally. Once the clutch is out and the plastic fan removed you can easily compare with pics online and figure out what you have, as long as it's one of the common ones (aisin black, aisin blue, eaton). Folks report good results with a rebuilt Eaton but I replaced mine with an Aisin blue.

Good pics of the Eaton here:

They all work the same way roughly though the internals vary a bit as does oil capacity. Regarding evaluating an old clutch I'd say the main points are below. I'd trash the clutch if isn't a yes on all of these points:
  • Is it one of the known/trusted variants?
  • Does it hold oil without leaking?
  • Is the bearing smooth/quiet?
  • Does the temp spring and plate rotation mechanism work smoothly?
    • Can test this with a heat gun if it's assembled, just watch to see if the input shaft turns, it's easier to see this with it split in half.

I'd guess that 15k or higher CST will work fine for your location. I'm running 15k CST in my Aisin blue hub and have driven around a lot of the country (towing in summer included) with good results. In terms of oil, making sure it has enough oil in it may be more important than, or just as important as, the weight. These days folks are typically running heavier oils than 15k CST as I understand it.

The temp at which the fan starts to open is also very important and seems likely to be off on an older unit given the heat cycles it will have seen.

With a new or old clutch you need to check/set the opening temps in my opinion. To do this, put the front half of the clutch in a double boiler, with a candy thermometer in the water and closely watch to see at what temps the oil ports start to open, are half open and are fully open. Record those temps, adjust as needed and then test/monitor engine temps to verify your adjustment. Correlate your typical operating temps with the noted fan clutch opening temps to help you track adjustments/performance.

You don't want the fan clutch to open too soon. Keep in mind that the coolant thermostat will likely open around 180 degrees (coolant temp) and more air through the rad below that temp is just wasted HP/Fuel. Air passing through the radiator will result in a different temp at the fan clutch so the setup numbers on the clutch won't directly match coolant temps.

My goal was to keep the coolant temps below 210F when pushing hard. When I first purchased my Aisin blue hub I couldn't drive to my house (at the top of a hill) and then idle without the AC shutting off (this happens around 220F). I changed the clutch oil (to 15k cst) and it was better but still didn't pass that test. I set the ports to start opening sooner and that resolved the issue. I ended up setting it so that the small hole is 50% open at 110 degrees. Side note: I had cleaned and sealed the radiator/condensor, etc. before turning to the fan clutch to dial in temps.

This is 1 banana work in my opinion. It's also effective and satisfying. The following should fill in gaps in what I've written above though there are other threads out there aplenty. Keep in mind that there is some variety in opening temps and oil weights used from thread to thread and over time.

hmm that other thread makes me think I might have the Eaton unless it was changed to some aftermarket part at some point. The question ism would it be more cost/time-effective to bolt in a blue hub or put 50 ml of 20k fluid in the Eaton, if that is in fact what I have.
 
Joined
Apr 9, 2013
Messages
1,623
I'll add that your 1997 fan clutch is due to be replaced. It's a 25+ year old, mission critical part at this point. Overheating your rig can grenade your HG. If you aren't selling your Cruiser next week, and you aren't stressed for the cash, just replace it.
I bought a blue hub Aisin some years back and drained it and filled it with 15K and I now very rarely see temps above 210 even running in the heat of day in the SoCal deserts. Changing out my fan clutch was the last thing I did after thermostat, radiator, flushes, all hoses, etc., and changing the fan clutch was the thing that finally brought my temps down. It's worth it to just get 'er done, especially if you off-road the vehicle or are ever far from home. Just my two cents.
 

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
I'll add that your 1997 fan clutch is due to be replaced. It's a 25+ year old, mission critical part at this point. Overheating your rig can grenade your HG. If you aren't selling your Cruiser next week, and you aren't stressed for the cash, just replace it.
I bought a blue hub Aisin some years back and drained it and filled it with 15K and I now very rarely see temps above 210 even running in the heat of day in the SoCal deserts. Changing out my fan clutch was the last thing I did after thermostat, radiator, flushes, all hoses, etc., and changing the fan clutch was the thing that finally brought my temps down. It's worth it to just get 'er done, especially if you off-road the vehicle or are ever far from home. Just my two cents.
Hmm I've read on here that new fluid can restore them to good as new as long as they aren't physically broken. I wasn't aware the part itself was a consumable. I'm not opposed to replacing with an AISIN blue hub if that's the best option though
 
Last edited:

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
Another related question on the water pump: I have a spare AISIN in the truck, but do these slowly degrade over time or suddenly fail and/or start leaking?

In other words, would a PM water pump replacement help being temps down, or do they usually wither work properly or not at all? In my current situation I want to avoid replacing things that aren't broken.
 
Joined
Apr 9, 2013
Messages
1,623
I've read on here that new fluid can restore them to good as new as long as they aren't physically broken. I wasn't aware the part itself was a consumable.
I had an Eaton clutch, which I R&R'd per Tools R Us' advice (we exchanged direct messages, and I read many posts about it). I thought my R&R'd Eaton with new oil was going to work just fine and it didn't. Replacing it finally brought my temps down. That's just one data point, and if you reoil and retune yours it might work fine. I tried to do that first as well, there's no harm in trying especially if you can watch your temps with an OBD reader, etc. Good luck.
 

JunkCrzr89

Competent Ignoramoose
Joined
Jul 21, 2019
Messages
4,647
Location
Colorado
hmm that other thread makes me think I might have the Eaton unless it was changed to some aftermarket part at some point. The question ism would it be more cost/time-effective to bolt in a blue hub or put 50 ml of 20k fluid in the Eaton, if that is in fact what I have.
The brand doesn’t really matter if you “rebuild” it yourself. Dumping 15-20k in an Eaton is no different than dumping 15-20k in an Aisin.
 

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
I had an Eaton clutch, which I R&R'd per Tools R Us' advice (we exchanged direct messages, and I read many posts about it). I thought my R&R'd Eaton with new oil was going to work just fine and it didn't. Replacing it finally brought my temps down. That's just one data point, and if you reoil and retune yours it might work fine. I tried to do that first as well, there's no harm in trying especially if you can watch your temps with an OBD reader, etc. Good luck.
Interesting. I’m watching my temps closely and the hottest I’ve seen is 215 while under load, so I’m hoping my cooling system just needs fine tuning and not major work. From your example might just order a new AISIN if the price is right.
The brand doesn’t really matter if you “rebuild” it yourself. Dumping 15-20k in an Eaton is no different than dumping 15-20k in an Aisin.
I think they vary in fluid capacity and have subtle differences in how they’re drained most effectively, just from what I’ve researched.
 
Joined
Nov 9, 2012
Messages
12,978
Location
Olathe, KS, USA
Also consider your thermostat.

I had about 100K on my cooling system and was experiencing overheating (226°F) when dragging a trailer and it turned out that my T-Stat was not opening all the way anymore.

I had changed out my fan clutch with an Aisin from Rockauto and it made zero difference. My fan clutch was either original black hub or was a Toyota replacement at 145K when the PO did the head gasket on my truck.

I am planning on installing heavier fluid in my fan clutch now because I feel it could be better.
 

JunkCrzr89

Competent Ignoramoose
Joined
Jul 21, 2019
Messages
4,647
Location
Colorado
Interesting. I’m watching my temps closely and the hottest I’ve seen is 215 while under load, so I’m hoping my cooling system just needs fine tuning and not major work. From your example might just order a new AISIN if the price is right.

I think they vary in fluid capacity and have subtle differences in how they’re drained most effectively, just from what I’ve researched.
If you’re that concerned, just buy an already modified blue hub Aisin from @landtank and forget about the rest.

 

Ozark Bushwalker

SILVER Star
Joined
Aug 20, 2021
Messages
952
Location
Northwest Arkansas
Also consider your thermostat.

I had about 100K on my cooling system and was experiencing overheating (226°F) when dragging a trailer and it turned out that my T-Stat was not opening all the way anymore.

I had changed out my fan clutch with an Aisin from Rockauto and it made zero difference. My fan clutch was either original black hub or was a Toyota replacement at 145K when the PO did the head gasket on my truck.

I am planning on installing heavier fluid in my fan clutch now because I feel it could be better.
Yeah I’m not sure if 215f under load is considered overheating or not. It always cools down to under 200 when the grades level out.

I thought usually under 220f was operational for cars in general, but some say the 1fz should be kept under 203. Regardless I’d like to see my temps about 10f lower than what I see now.
 

Users who are viewing this thread

Top Bottom